Warp control in a loom for weaving



Sept. 6, 1960 E. PFARRWALLER WARP CONTROL IN A LOOM FOR WEAVING Filed April 8, 1957 Lmw i.

JNVENTOR. ER W/N PFARIPWA LL El? ATTOK/VEK 2,951,509 WARP CONTROL IN A LOOM FOR WEAVING Erwin Pfarrwaller, Winterthur, Switzerland, assignor to Sulzer Frres, S.A., Winterthur, Switzerland, 21 corporation of Switzerland The present invention relates to an apparatus for controlling the warp in aloom for weaving in which apparatus means are provided for damping vibrations.

The apparatus to which the damping means according to the invention are applied may be of the type disclosed in my copending application Serial No. 406,116, filed January 26, 1954, which has matured into Patent No. 2,819,734 on January 14, 1958.

The novel features which are considered charactertstic of the invention are set forth with particularity in the appended claims. The invention itself, however, and additional objects and advantages thereof will best be understood from the following description of embodiments thereof when read in connection with the accompanying drawing in which:

Fig. l is a diagrammatic illustration of a loom for weaving and particularly of the device for tensioning the warp and for controlling the warp supply, and of vibration damping means according to the invention;

Fig. 1a is a diagrammatic part sectional view of a modified vibration damper arrangement;

Fig. 2 is a diagrammatic illustration of a brake for damping the movements of the warp tensioning lever;

Fig. 3 is a cross sectional view of an adjustable brake for the warp tensioning beam;

Fig. 4 is a small scale top view of the brake shown in Fig. 3.

Like parts are designated by like numerals in different figures of the drawing.

Referring more particularly to Fig. 1 of the drawing, numeral designates a warp beam from which a warp 11 is unwound. The warp is laid over a warp tensioning beam or whip roll 12. Either end of the latter has a journal which is supported by a tensioning lever 13. The levers 13 swing on pins 14 mounted on the frame of the loom. Each lever 13 has an arm 15 provided with recesses or notches 16 for receiving a bolt 17 which is connected by means of a link 18 with a tension spring 19. By changing the position of the bolt 17 on the arm 15 the tensioning effect of the device 12 to 19 on the Warp can be changed. The warp 11 moves in the conventional manner from the tensioning beam 12 through warp feelers 21 and thereupon through heddles 22, and through a reed 23. After insertion of the weft threads 24, the fabric 25 is formed which travels around a beam 26, a fabric movement control beam 27, and a yieldingly supported roller 28 which presses the fabric against the beam 27. Thereupon the fabric is wound on a cloth beam, not shown.

A warp control mechanism is provided by rotating the warp beam 10. This mechanism includes a clutch 31, 32 which is driven by a shaft 33 connected with the loom drive and which periodically or interruptedly drives a gear 37 of the warp beam 10 by means of a worm 34 and gears 35 and 36. An arm 38 is connected with the lever 13 for actuating a lever 41 by means of a link 39, lever 41 actuating an elbow lever 42 which determines the position of the clutch part 32.

nited States atent The clutch disc 31 is axially movable on the shaft 33,- but cannot rotate relatively to the shaft. The disc 31 is provided with a cam 43 which is engaged by a cam follower roller 44 rotatably supported on the frame of the machine. The clutch disc 32 is also axially movably but not relatively rotatably mounted on a shaft 45 for a pinion 34. A brake disc 46 is rigidly connected with the clutch disc 32. A casing 47 is pressed against the disc 46 by means of a spring, not shown, and located within the casing 47. The latter is rotatable relatively to the disc 32. The clutch disc 31 is periodically axially moved towards the disc 32 by the cooperation of the roller 44 and the cam 43 whose axial extension is greater than the clearance or between the disengaged clutch discs 31 and 32 so that the disc 31 pushes the disc 32 to the left thereby disengaging the brake disc 46 from the casing 47. Uponengagement of the discs 31 and 32 the shaft 45 is rotated and the warp beam 10 is rotated through an angle depending on the duration of the engagement of the clutch 31, 32.

The casing '47 is supported by means of pins 49 on a fork 48 of an elbow lever 42. The latter has a horizontal arm to which a pin 51 is rigidly connected. The pin 51 swingably carries a slide member which slides in a circular slot 52 in the lower part of the lever 41. The center of the curvature of the slot 52 does not coincide with the fulcrum of the lever 41. Depending on the position of the tensioning beam 12 below or above the horizontal O, the pin 51 is lifted or lowered so that the duration of engagement of the clutch 31, 32 and thereby the angular movements of the warp beam 11 are increased or decreased. The warp 11 is tensioned by the device including the tensioning beam 12, the tensioning lever 13, and the spring 19. The device for controlling the supply of the warp 11 to the loom includes the member 38 which is rigidly connected with the lever 13, the connecting rod 39, the levers '41 and 42, and the clutch 31, 32. The position of the tensioning beam 12 controls the amount of Warp released from the Warp beam 11.

When weaving, particularly when weaving at a great number of picks per minute and producing a densely beaten fabric, the warp 11 is elastically tensioned when ever a weft thread is beaten up. The warp acts like a spring and the portion of the Warp between the warp beam 10 and the apex of the shed Where the fabric is formed vibrates more or less depending on the length of the warp threads between two supports and the number of picks per minute. The amplitude of the vibrations of the tensioning beam 12 which is under normal operating conditions between the lines e and e may be considerably increased.

This is particularly the case if the change of the position of the tensioning beam 12 is used for controlling the rotation of the warp beam and if the bearings of the tensioning beam 12 and of the tensioning lever 13 are so constructed as to produce very little friction for obtaining a fine control of the operation of the Warp beam and avoiding irregularities in the fabric 25.

An increase of the amplitude of the movement of the tensioning beam 12 increases stress on the warp 11 and parts connected therewith. Since the vibrations of the warp system cause an increase of the up and down movement of the tensioning beam 12, the mass of the latter affects and additionally periodically loads the warp 11.

In order to reduce the vibrations in the system of the tensioned warp, brake means, shown in larger scale in Fig. 4, may be interposed between the tension beam 12 and at least one of the tensioning levers 13 for impeding the rotation of the tensioning beam 12. These brakes means will be described later. This arrangement interferes least with the sensitivity of the warp control.

A hydraulic vibration damper may be arranged in the linkage between the warp tensioning beam 12 and the device for releasing the warp. In this case, a dash pot 59 is interposed in the connecting rod 39, the piston rod being pivoted to the lever 38 and the cylinder of the dash pot being pivoted to the lever 41 (Fig. 1a).

Instead of the brake device for the whip .roll 12 a brake drum 61 may be rigidly connected with the tensioning lever 13 coaxially of the pins 14, as shown in Fig. 2. A brake band 62 is laid around the brake drum 61, one end of the brake band being connected to the frame of the weaving machine and the free end 63 of the brake band being connected with a brake lever in the conventional manner. A weight 6.4 is movable on the brake lever for adjusting the brake effect of the brake. Instead of the Weight 64 a spring may be used in the conventional manner.

It has been found that the last mentioned arrangement interferes least with the sensitivity of the warp control.

In the brake device shown in Fig. 3, the tensioning lever 13 is provided with a bolt 65 which loosely supports a clamp or bracket 66. The latter has two arms or brake shoes 67 and 68 the insides of which are provided with brake linings 76, the legs 67 and 63 embracing an end portion 70 of reduced diameter of the tensioning beam 12 or of a shaft 80 supporting the tensioning beam. The bracket 66 is placed on the inside of a tensioning lever 13. A bolt 71 extends through a hole 72 inthe upper end of the leg 68 and is screwed into a threaded bore in the upper end of the leg 67. A compression coil spring 73 is laid around the right end of the bolt 71 and abuts against the upper end of the leg 68. The tension of the spring 73 can be adjusted by manipulating a nut 74, a lock nut 75 being provided for fixing the position of the nut 7'4. The force of the spring 73 presses the legs 67 and 68 against each other so that the brake shoes exert a desired brake pressure on the end of the tensioning beam 12. The resiliency of the bracket 66 is afiorded by the clearance between the bolt 65 and the lower portion 77 of the bracket surrounding the bolt which portion is relatively thin. Since the bolt 65 prevents rotation of the bracket 66, rotation of the tensioning beam 12 in the tensioning lever 13 which is caused by the advancing Warp 11 is braked to a predetermined extent. The pressure of the spring 73 is preferably so adjusted that the tensioning beam 12 is still permitted to rotate when its axis swings between the positions e and e, and the Warp 11 does not slide on the beam 12.

Braking is efiected in such manner that the rotational oscillations of the beam 12 caused by the up and down movement of the beam are damped by the brake effect of the shoes 67 so that the Warp slides on the tensioning beam 12 in a degree which depends on the braking effect.

This sliding of the warp increases friction between the.

warp and the tensioning beam and dampens the vibrations. The amplitude of the swinging movement of the tensioning lever 13 is limited to the distance between e and e when the braking effect of the damping device, i.e., of the bracket 66 is correctly adjusted by suitable tensioning of the spring 73'. V

I claim:

1. In a loom for weaving, a warp beam, a whip roll receiving warp from said warp beam, tensioning levers swingable on a stationary fulcrum and rotatably supporting said whip roll, tensioning means permanently connected to at least one of said levers for permanently urging said levers and said whip roll to assume a warp tensioning position, and permanently acting brake means connected to at least one of said tensioning levers and permanently engaging said whip roll for impeding rotation of said whip roll as well as swinging of said levers.

2. In a loom for Weaving as defined in claim 1 and wherein said whip roll has end journals and said brake means includes clamp means swingably supported by the respective tensioning lever and embracing the respective end journal, and adjustable means for adjustably closing and pressing said clamp means against the respective end journal.

3. In a loom for weaving according to claim 2 in which said clamp means is in the form of a bracket having two arms straddling the respective journal, the portion of said bracket from which said arms extend being resilient, permitting movement of said arms towards and from each other, and having a bore, a bolt being mounted on the respective tensioning lever, said bolt having a smaller diameter than said bore and extending through said bore for loosely swingably supporting said bracket.

References Cited in the file of this patent UNITED STATES PATENTS 2,250,833 I-Iill July 29, 1941 2,370,022 Dudley Feb. 20, 1945 2,425,909 Wilhelm Aug. 19, 1947 2,755,823 Hunt July 24, 1956 2,819,734 Pfarrwaller Jan. 14, 1958 FOREIGN PATENTS 772,796 France Aug. 20, 1934 

